Safety load equalizing and draft stabilizing coupling device for automobile towed trailers



MATHISEN 2,597,657

ING

May 20, 1952 M. H.

SAFETY LOAD EQUALIZING AND DRAFT STABILIZING COUPL DEVICE FOR AUTOMOBILETOWED TRAILERS 2 SHEETS-SHEET 1 Filed June 25, 1951 [kl/91213.7.fibula/13622 2,597,657 ND DRAFT STABILIZING COUPLI DEVICE FOR AUTOMOBILETOWED TRAILERS M y 1952 M H. MATHlSEN SAFETY LOAD EQUALIZING A 2SHEETSSHEET 2 Filed June 25, 1951 Htzwwey Patented May 20, 1952 SAFETYLOAD EQUALIZING AND DRAFT STABILIZING COUPLING DEVICE FOR AUTOMOBILETOWED TRAILERS Martin H.- Mathisen, North Hollywood, Calif.

Application June 25, 1951, Serial No. 233,424

9 Claims.

This invention relates to improvements in a safety loadequalizing anddraft stabilizing. coupling device for automobile towed trailers, whichdevice comprises essentially a drawbar equipped with ball and socketproviding an articulated draft connection between the automobile andtrailer.

In devices of this character which must not only provide quick and easyattachment and detachment of the vehicles but which must also permit therequired relative movements between these vehicles, it has been foundthat such a connecting device must also possess other required featuresfor greater safety, comfort and economy in operation. I

Such features comprise, a safety hitch as auxiliary to the ball andsocket connection, which it spans; an intermediate manually operabledraft bar and trailer frame liftin and sag preventing device; aresilient support for these articulated connected parts; draftequalizing and sway preventing means; and manual adjustable as well asself tensioning means associated with opposite sides of the articulatedconnection for righting and automatically aligning the draft and towdevices under all road and operating conditions.

Where the wheels of the trailer are disposed rearwardly of the center ofload, which is generally the case, the unbalanced weight istransferredthrough a sagging articulated drawbar connection to exert downwardpressure on the extreme rear end of the automobile frame. The result isto greatly overload the rear wheels of the automobile and toproportionately reduce the weight on the front wheels to a point wheresteering becomes difficult and unsafe.

An example of such unbalancing of the wheel loads may be observed fromthe following:

Point of weighing with trailer attached: Pounds Front wheels 1900 Rearwheels 3900 A primary object of the invention is,. therefore, to providea readily operable, quick detachable draft coupling including the usualballand socket connection and a resilient and self-tensioning draft andauxiliary supportin means operatively associated therewith whereby thedraft end of a two-wheel trailer, for instance, may be quickly andreadily raised and aligned with the frame of the towing, automobilewithout the aid of ac cessories or dollies. Said means serving tofuncv:tion thereafter to resiliently support; equalize 2 and distributethe added down weight over all four wheels of the automobile.

A further object of the invention is to provide selective andindividually adjustable lifting, leveling and automatic self-tensioningmeans at opposite sides of the drawbar and its articulated connectionwith the trailer, to compensate for variations in trailer drawbarWeight, list and.

tendency to sway.

A still further object of the invention is to provide a supplementaltrailer'coupling device which spans the ball and socket connectionproviding a safety coupling device, which in itself is operative toraise and resiliently support the usual sagging ball couplinganddraftbar between a two-wheel or other unbalanced trailer and theconnected automobile, as well as to automatically stabilize and maintainstraight line draft between the trailer and automobile under abnormaltendencies toward side sway and bounce.

Another object of the invention is to provide a hitch device of thecharacter above referred to which is simple in construction and which isreadily applicable as an attachment to automobile-trailer hitches now inuse.

A more specific object of the invention is to provide an improved loadraising and equalizing structure in association with the connectionbetween the free end of a drawbar projecting'from the rear of anautomobile and thefront end of aforwardly projecting frame extension ona trailer and which structure is particularly characterized in thatitincludes a pair of elongated resilient rods which at corresponding endshave pivotal connections with the drawbar at opposite sides of thepivotal connection between the drawbar and extension and which rods aremaintained under substantial tension by flexible members depending. fromthe extension adjacent the trailer body and whose lower ends areadjustably connected to the rear ends of the rods, and the stressed ortensioned rods in their normal operative position being under minimumstress and relative movement between the automobile and trailer placingthe rods under greater stress whereby they react toward normal position.

Other'objects and advantages of the invention will become apparent inthe course of the following detailed description, taken in'connectionwith the accompanying drawings, wherein:

Fig. 1 is a side elevational view of the device showing same connectedwith the usual automobile-trailer hitch in its inoperative saggingposition. which it assumes at the time of making 3 or breakingconnection between the automobile and trailer;

Fig. 2 is a view similar to Fig. 1 but showing the device in its raisedor operative load equalizing position;

Fig. 3 is an elevational view of one of the two weight and tensionequalizing rods included in the device;

Fig. 4 is a top plan view of the tapering forward end of a trailer frameand an associated automobile drawbar hitch showing the improved deviceoperatively associated therewith;

Fig. 5 is a perspective view of the assembly and improved device inoperative association with an automobile-trailer hitch, as shown in Fig.4 and tensioned for normal draft or towing operation.

Referring now in detail to the drawings, T designates a trailer and Adesignates a draft automobile. The trailer T is provided with the usualhitch extension E including outwardly converging frame members in theform of beams B, the forward ends of which are jointed to provide acoupling member S. This coupling member is hollowed out at its undersideto provide the usual downwardly opening socket for receiving the ballcoupling 1) carried by an upward extension e of a drawbar d suitablysecured to the frame of an automobile A, beneath the rear end of thebody thereof.

In the absence of load equalizing means this articulated connectionbetween an automobile and trailer appears substantially as shown in Fig.1, wherein the pivotal connecting member S, b are substantially belowthe rear end of the extension E. This sagging condition is caused by theunbalanced forward end of the trailer forcing the rear end of theautomobile down under substantial weight with a corresponding reductionof weight on the front wheels of the automobile. The condition justdescribed has been recognized and many devices have been proposed toovercome same with only partial results.

It is, therefore, the purpose of this invention to eliminate the sag ofthe usual ball and socket pivotal connection between an automobile and atrailer with a resulting distribution of weight over the front and rearwheels of the automobile, as well as the displacement of weight to therear of the trailer.

The improved structure according to this invention comprises a sleeve orsocket member ID which is rigidly secured, as by welding, to each sideof the draftbar extension e with their vertical axes parallel and intransverse alignment with the vertical axis of the ball b.

The improved construction further includes a pair of resilient rods IIwhich have sleeve engageable angular end bearing portions I2 which, asindicated in Fig. 3, have their axes at a substantial angle at to aplane normal to the axis of the body portions I3 of the rods.

These bearing end portions I2 are freely receivable in the lower openends of the sleeves I and whose upper ends are closed as indicated at I0to serve as thrust bearings for the free ends of the end portions I2 andthe end portions are supported within the sleeves for rotation aboutvertical axes.

The rods II are reenforced at the elbows between portions I2 and I3 bysubstantially thickening same, as is indicated at I4, for a purposelater to appear.

The rods II are further provided with collars I adjacent their rear endsand which collars are the load on the chains.

4 adjustable therealong and secured to the rods as by means of bolts I6,extending through ears II.

A flexible member, herein shown as a sprocket chain I8, has its lowerend rigidly secured to each collar I5, by any suitable means and thechains extend over sprocket wheels I9 disposed within casings 2|]through which extends a shaft 2 I, supported by and projecting laterallyof the beams B and to which the sprocket wheels are secured. The shaft2I is supported in suitable bearings 22 which are rigidly supported on abase plate or other frame member 23 disposed between and suitablyrigidly secured to the rear ends of the beams B.

As is more clearly indicated in Fig. 2, the casings 20 preferablyinclude arched covers 24 which are pivotally connected to the bodyportions thereof as at 25. The purpose of having access to thesesprockets is for adjustably placing the chains thereon as occasion mayrequire. The covers are preferably provided with knobs 25 forfacilitating the raising and lowering thereof.

As is further shown in Fig. 2, the walls of the casings below the pivots25 prevent displacement of the free ends of the chains from operativeengagement with the sprocket wheels. Means are provided for impartingrotation to the shaft 2| and such means in an acceptable form maycomprise a housing 21, disposed between one of the casings 20 and anadjacent shaft bearing 22.

Rotatably supported in the housing 21 is a shaft 28 (Fig. 1) which isprovided with a worm 29 in meshing engagement with a gear 30 secured tothe shaft 2I. The outer projecting end of this shaft 28 may be providedwith a polygonal socket SI for removably receiving a suitable operatingcrank W for imparting rotation to the shaft. In order to more firmlysupport housings 21, brackets 21a may be provided as indi cated.

While various other shaft operating means may be provided, the worm andgear arrangement provides for easy operation and also serves as aneffective lock to hold the shaft in any desired rotated position withoutratchets etc.

The improved auxiliary hitch and load stabilizer is highly simple inconstruction in that it comprises only a pair of bearing sleeves orpivot members, a pair of resilient rods, a pair of chains, and chainoperating means.

The improved auxiliary hitch and load Stabilizer is shown in Fig. l ininitially attached and inoperative position and wherein the usual balland socket hitch is illustrated in the sagging position which it assumesin the absence of an equalizing and stabilizing means. To render thedevice operative, the shaft 2I is rotated through the cooperating wormand gear 29, 30 whereby rotation is imparted to the sprocket wheels I9.

Upon rotation of the sprocket wheels, which will amount to no more thana single rotation thereof, the chains I8 will tension the free or rearends of the rods I I, upwardly to substantially the position shown inFig. 2.

This lifting of the rear ends of the rods II will result in bending ofthe rods and importation of substantial stress therein. The tensioningof the rods from the trailer extension will result in upward pressure onthe pivoted ends I3 of the rods in an amount substantially equal to Thisoperation will result in lifting of the sagging ball and socket joint S,b to a position wherein the trailer extension E will be substantiallyhorizontal and the load will be properly equalized not only on the frontand rear wheelsof the automobile A, but also on the trailer body.

The enlargements H at the knuckles of the rods II are disposed justbelow the lower open ends of the bearing'sl'eeves I0. These thickenedportions serve tostrengthen the. angular bent area of the rods betweenthestraight' portions [3 and I3 and thus'cause uniform distribution ofthe bending force throughout the length of the rod portion it, betweentheenlargement l4 and the adjustable sleeve l5, as shown in Fig. 3.Breakage through sharp bending and resulting crystallization of themetal at the knuckles of the rods is thus presented.

The structure in the operative position shown in Figs. 2 and 5 is bothyieldable and flexible and serves to support and maintain the automobileand trailer in properly balanced relation under all road drivingconditions. It is to be particularly noted that with the structure innormal operative position, as in Figs. 2 and 5, the substantial stressin the rods I I is at a minimum. Upon turning or upon encounteringirregularities in the roadway, the rods II will also pivot in thebearing sleeves l0, causing the opposite ends of the rods to moveforward or backward and/or to one side or the other. The tensioningchains will then be forced to a position out of their normal verticalpositions, with the result that the free ends of the rods will be drawnup nearer to the supporting beam B resulting in increased tensioning ofthe rods under such deflection. Accordingly such increased tension willact to again reestablish a normal position of the rods with the resultthat the hitch will tend to right itself and the attached vehicles underall driving conditions.

There are two independent yet cooperative couplings provided by thesocketed frame extension E and the pivoted rods H with the drawbar d,thus preventing accidental separation of the automobile and trailer. Ahitch possessing exceptional safety features results from thecombination and arrangement of parts herein shown and described.

While I have disclosed my invention in accordance with a singlestructural embodiment thereof, such is to be considered as illustrativeonly, and not restrictive, the scope of the invention being defined inthe sub-joined claims.

What I claim and desire to secure by U. S. Letters Patent is:

1. An auxiliary automobile-trailer hitch comprising a pair of elongatedvertical axis pivot means for attachment to the automobile at laterallyopposite sides of an articulated joint between same and the trailer, apair of normally straight spring rods having angular end portions snuglyreceivable within said pivot means for pivotal movement of the rodshorizontally only, a pair of generally vertically disposed flexiblesuspension members having corresponding ends thereof connected to thefree ends of said rods, and power means for support on said trailerabove said rods and operatively engaged with the opposite ends of saidflexible suspension members for bending and tensioning the rod.

2. The structure according to claim 1, wherein said angular end portionsof said rods are disposed at an angle of more than 90 to the elongatedbody portions thereof and the juncture of the angular end portion andelongated body portion being substantially thickened to resist flexingof said juncture.

comprising a pair ofelongated normally straight resilient rods havingcorresponding angularly disposed end portions pivotallysupported onvertical axes on said drawbar at laterally opposite sides of saiduniversal joint for horizontal pivotal movement only, said-rodsextending rearwardly *indiverging relation withtheir free ends disposedbelow said extension and adjacent said trailer, flexible suspensionmembers havin corresponding ends thereof secured to said free ends ofthe rods, and power means supported on said extension above said rods towhich the opposite ends of said flexible members are secured and. uponoperation of which the free ends of the rods are drawn upwardly with aresulting bending and tensioning of the rods, whereby said universaljoint connection is yieldably urged upwardly for substantialequalization of the load on the automobile and trailer.

4. The structure according to claim 3, wherein said end portions of therods are disposed at an angle of more than to the body portions thereofto provide for substantial tensioning of the body portions of the rodswith same supported substantially in horizontal position when in loadequalizing condition, and the angles between said end portions and saidbody portions being reenforced.

5. The structure according to claim 3, wherein said rod end portions arepivotally supported in sleeves rigidly connected to opposite sides ofsaid drawbar, and the upper ends of said sleeves being closed to providethrust bearings for the free ends of said rod end portions.

6. The structure according to claim 3, wherein said flexible memberscomprise sprocket chains, and wherein said power means include a shaftrotatably supported on said extension, sprocket wheels secured to saidshaft with which said chains are operatively engaged, and worm and gearmeans for rotating said shaft and retaining same in any rotatedposition.

7. In combination with an automobile-trailer hitch including a drawbarprojecting rearwardly of the automobile, an extension projectingforwardly of the trailer, and a universal joint connection between therear end of the drawbar and the forward end of the extension; loadequalizing and draft stabilizing means comprising a pair of sleevessecured to said drawbar at opposite sides of said universal jointconnection, and having closed upper ends, a pair of resilient rodsincluding elongated body portions and end portion in substantially rightangular relation thereto, said end portions being supported within saidsleeves for rotation about vertical axes, and manually operable meanssupported by said extension and including flexible members dependingfrom said extension and connected with the free ends of the bodyportions of said rods for raising same and placing said rods undersubstantial tension, whereby said end portions react on the closed endsof said sleeves to urge said universal joint connection upwardly forload equalization and draft stabilization.

8. The structure according to claim 7, wherein said flexible members arenormally in vertical position between said extension and said free endsof the rods, the said rotational support of the rods within said sleevesand said flexible members permitting said rods to move substantially ina horizontal plane upon turning of the automobile or upon irregularitiesin the roadbed, said movement of the rods causing said flexible membersto move out of their normal vertical positions with a resultingincreased tension in the rods and which increased tension automaticallyurges the rods to their normal stressed positions.

9. The structure according to claim 7, wherein said flexible members arelongitudinally adjustably connected to the elongated body portions ofsaid resilient rods.

MARTIN H. MATHISEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS 10 Number Name Date 2,453,941 Smit Nov. 16, 19482,549,814 Hume Apr. 24, 1951

